Wired have this article on using lasers to mimic voice commands for Alexa, Google Home and Siri. To summarise, the technique pulses lasers mimicking voice on the microphone and triggering a response from the device. These devices do offer user recognition in order to respond to either all commands or sensitive commands such as ‘unlock the front door’. Your voice is your biometric security here. We speak in public all the time and use phone lines that can be tapped. It wouldn’t be hard to steal your voice, particularly if you were in the public eye anyway like a politician or pop star. The hack would simply process your voice into a command and send it over to the device with laser (so effectively silently) and issue commands. Hmmm.